Wednesday, 7 September 2011


With a recent bout of extra hours at work have been a double edged sword – on one hand I have not had the time or energy to work on the Cobra much, but on the other it has boosted the funding! I have therefore been able to procure a significant set of parts from the US that are otherwise difficult or impossible to source in the UK. These include:
  •  A pair of aftermarket aluminium cylinder heads and head bolts
  • Roller cam shaft and lifters suitable for a fuel injected engine
  • A set of roller rocker arms
  • Cam position sensor housing (which normally replaces the distributor, but I will use only as an oil pump drive)
  • Appropriate head and port gaskets
  • Pushrod length checking tool
  • Billet piston ring compressor 
The main job with most of these parts is to digitise them so I can build up the engine CAD model in preparation for the manifold design – I’d better get out the measuring stick then!

Other progress has finally seen the completion of the Engine Control Unit customisation. I built the basic Megasquirt kit a while ago and combined all of the modifications that I wanted onto a custom designed auxiliary Printed Circuit Board. I have now finished incorporating this extra PCB into the enclosure and have successfully bench tested the system using an electronic ‘stimulator’ to mimic the engine signals and loads. My additions over the basic assembly are:

  • 4 coil drivers for wasted spark ignition
  • 5V square wave output tachometer signal
  • Second wide-band Exhaust Gas Oxygen (EGO) sensor input
  • Open collector ‘engine running’ signal to disable starter motor
  • Relay driver to control radiator fan

With these additional functions operational (well, flashing a bunch of LEDs on the stimulator board!), I can now move on to building up a hardware test bench to run the actual engine components (coils, injectors etc.) before attempting to control an actual engine.

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